In Yosemite there is an almost non-existent waterfall called “Horsetail Falls.” During the last two weeks in February if conditions are perfect, photographers and spectators can witness what appears to be molten lava spilling over the Falls, but what is, in fact, an illusion caused by the angle of the sun.

“Perfect conditions” means first, sunlight in a clear, perfect sky (despite the clouds and storms that are common in Winter.) Second, there’s just a two-week window; the setting sun is positioned correctly ONLY during the last two weeks of February. Last, there must be water trickling over the falls.